The electronic organizer (or databank or personal digital assistant--PDA, hereinafter referred to collectively as electronic organizer--is a useful electronic product which is able to store substantially large quantity of personal application information.
FIG. 1 illustrates the system schematics of an electronic organizer. As shown in the figure, an electronic organizer comprises: a microprocessor 1, a memory (RAM/ROM) 2 to store system program, application programs and other information, an LCD display 3 to output (display) information and a keyboard 4 as input device. The microprocessor 1 has a number of data/signal connectors through which signals and data are input or output, according to the specifications of the manufacturer of the microprocessor. In order to communicate with peripherals, the microprocessor shall have at least one "data-in" connector 12 and a "data-out" connector 11.
Due to the limitation of the functions and memory capacity of the electronic organizer, and due to the inconvenience in using the keyboard to input information, the electronic organizer is not capable of processing (operating) a large quantity of data and is not usually used to input a large quantity of data from the keyboard directly, although an electronic organizer is able to store large quantities of data. In general, when it is necessary to process a file stored in an electronic organizer, the file is first dumped to a personal computer and processed in the personal computer and the file so processed is transmitted into the electronic organizer. Similarly, when a large quantity of data is input into an electronic organizer, the data are first input into a personal computer and then transmitted to the electronic organizer. The above-said data-in connector 12 and the data-out connector 11 function as input or output channel for such transmission.
In the conventional art, an electronic organizer communicates with a personal computer through the common communication ports of the personal computer. Suited communication interfaces include an RS-232 port and a PCMCIA port. In order to conduct the communication between a personal computer and its peripherals, it is necessary to provide a special communication interface device. In the conventional art, the communication interface may be classified into three categories, as follows:
The first is the wireless communication interface. In most cases, the communication is conducted with an infrared emitter and a optical sensor. The wireless communication approach includes all kinds of infrared communication interfaces, varying from a high speed IrDA communication interface which speed can be about 4M bit/sec., to a low speed non-standard communication interface. Among them, the IrDA interface provides the function of high speed transmission of information while the manufacturing cost is relatively high. If the CRT display is used as a light emitter, the manufacturing cost may be reduced to half. However, the transmission speed of the CRT display is relatively low (about tenths of a second) and the CRT may not provide the function of two-way transmission.
The second approach is to communicate with an interface card, such as a Personal Computer Memory Card International Association (PCMICIA) card. This approach provides higher transmission speed and larger transmission capacity. Its disadvantages include that a PCMCIA interface is not provided in a desktop personal computer and that the manufacture cost for a PCMCIA card is still relatively high.
The third approach is a line-in communication. The most popular way is through an RS-232 port or a printer port. An electronic organizer may communicate with a personal computer through the RS-232 port or the printer port with a cable with a standard 9 pin or 25 pin adapter. These communication ports are provided in almost every desktop or notebook computer. However, the RS-232 port is always occupied by a mouse or a modem and the printer port by a printer. While RS-232 port or the printer port shall be used, it will be necessary to detach the original adapter and connect the port to the electronic organizer. In the case of the RS-232, due to the fact that the RS-232 port requires dual supply voltages (both positive and negative), additional circuitry must be provided so as to adjust the voltage level of the RS-232 into that acceptable to the logic circuit of the recipient. As for the printer port, although it is a parallel port which provides higher transmission speed, it is not suited to connect with small scale equipment like the electronic organizer because of the large scale of the cable line and the adapter.
Besides the above-mentioned approaches, there are communication interfaces like Ethernet, Universal Serial Bus (USB) etc. These approaches are designed for communications under higher speeds and are not considered suited for the communications between a personal computer and an electronic organizer.
There is need in the industry to provide a simplified communication interface device to enable the communications between a personal computer and an electronic organizer.
There is also a need in the industry to provide a novel communication interface device between an electronic organizer and a personal computer whereby the resources of the personal computer may be used without requiring additional equipment.